1. Field of the Invention
The present invention relates generally to the field of computer networking, and in particular to a method for obtaining a user-controlled parameter from a client device which communicates with other devices through a proxy.
2. Related Art
It is known to deploy a network proxy, or proxy server, as an intermediary between one or more client computers and an external network such as the Internet. Network proxies are described generally in Ian S. Graham, HTML Source Book: A Complete Guide to HTML 3.0 (2d ed. 1996). A network proxy is commonly used in conjunction with so-called xe2x80x9cfirewallxe2x80x9d software to protect a local area network (LAN) from unauthorized access over the Internet. Such a firewall, typically installed on a gateway computer that links a LAN to the external world, restricts externally-originated TCP/IP (Transmission Control Protocol/Internet Protocol) packets from entering the local network, thereby protecting local devices from hazards such as unauthorized access. The firewall, however, also prevents network users from directly accessing external resources such as the World-Wide Web (xe2x80x9cthe Webxe2x80x9d). Network proxies are often used to address this shortcoming. See Graham, at 403.
Network proxies are usually configured to have free access to both internal LAN resources and external resources, and can safely pass data back and forth across the firewall. Users may then be given safe, though indirect, access to Web resources by configuring the user""s Web browser to reference the firewall proxy instead of external servers (e.g., content servers). When the Web browser is used to retrieve information from the other side of the firewall, it sends a request to the firewall proxy, which then completes the request and passes the result back over the firewall to the requesting device.
One of the side-effects of using a firewall or other network proxy to control a client device""s access to external network resources is that requests received by a content server, for example, although generated by a particular client device, will designate the IP address of the firewall proxy as the requesting device. In other words, the ultimate recipient of the request cannot determine the IP address of the client device that actually originated the request. This presents a problem for network applications capable of providing services customized according to user-specified preferences. A remote network proxy or content server cannot reliably use the IP address in a received request to determine such user preferences because many users may be accessing the remote device through the same proxy. Accordingly, there is a need for a method and apparatus by which a network device, such as a remote network proxy or a server, can obtain user-specific information from a client device which communicates with that network device through a firewall or other proxy.
The present invention relates generally to methods and apparatus for detecting a user-controlled parameter from a client device residing behind a proxy. Embodiments of the invention may be used, for example, to enable a network device, such as one capable of providing customized transcoding services, to acquire user-specified preferences from a client device which accesses that network device through a firewall or other proxy.
According to one particular embodiment of the present invention, a method for obtaining a user-controlled parameter from a client device arranged behind a network proxy includes the steps of receiving a request originated by the client device; transmitting a responsive request to the client device, where the responsive request includes a query mechanism to elicit a user-controlled parameter from the client device; and receiving the user-controlled parameter from the client device.